A temperature sensor is a sensor that senses temperature and converts the temperature to an available output signal, and mainly includes a thermal resistance temperature sensor, a thermistor temperature sensor, a thermocouple temperature sensor and an integrated P-N junction temperature sensor. As technologies develop, an infrared radiation sensor, a pyroelectric detector, a MOS field-effect transistor infrared detector and an optical fiber temperature sensor have increasingly more applications. The diversified temperature sensors have respective advantages and defects. Several types of most commonly used temperature sensors are thermal resistance temperature sensors, thermistor temperature sensors and thermocouple temperature sensors, and they are applied in slightly different scenarios. A thermistor is generally made of a monocrystalline semiconductor material or a polycrystalline semiconductor material, and is extremely sensitive to temperature. A resistance value thereof will change along with temperature in a stepped manner, and the change is generally non-linear. A thermocouple temperature sensor is very suitable for high-temperature measurement, but has an undesirable measurement effect in a negative temperature interval. Moreover, precautionary measures should be taken for cold-junction compensation, reference-junction temperature control, and lead compensation of the thermocouple temperature sensor, and thus, the measurement process thereof is very complex. A resistance value of a thermal resistance temperature sensor exerts a desirable linear relationship with temperature, and has a good stability. Therefore, the thermal resistance temperature sensor is a most commonly used temperature detector in a medium-low temperature range (−200° C. to 650° C.).
At present, the thermal resistance temperature sensors mostly use platinum as the thermal resistance sensitive material, which have the following major advantages: a resistance value of the metal platinum changes as the temperature changes, forming a basically linear relationship, and the change has desirable reproducibility and stability. Therefore, such thermal resistance temperature sensor has high measurement precision and a broad application temperature range, and is a most commonly used temperature detector in a medium-low temperature range (−200° C. to 650° C.). Another commonly used thermal resistance material is nickel, which has a temperature coefficient of resistance being 1.7 times that of platinum, and has a higher sensitivity. Therefore, the expensive platinum thermal resistor may be replaced with a nickel thermal resistor in a case having a relatively low precision requirement. Compared with platinum and nickel, copper has the best linearity, and has a temperature coefficient of resistance higher than that of platinum. However, copper has obvious defects: the low resistivity causes low sensitivity and low precision, and copper is easily oxidized, corroded and the like. The above defects severely limit applications of copper in temperature detection, and people have not paid much attention to copper over a long period of time.